The present disclosure relates to a developing device, and to an image forming apparatus incorporating a developing device. More particularly, the present disclosure relates to a developing device including a regulating member for regulating the thickness of developer on the surface of a developer carrier, and to an image forming apparatus incorporating such a developing device.
A conventionally common developing method adopted in image forming apparatuses using an electrophotographic process typically uses powdery developer and involves a process including visualizing an electrostatic latent image formed on a developer carrier such as a photosensitive drum with the developer, then transferring the visualized image (toner image) to a recording medium, and then fixing the image.
Developer is broadly classified into two-component developer comprising toner and magnetic carrier and one-component developer comprising non-magnetic or magnetic toner alone. For example, a developing device using a magnetic one-component developing method stores magnetic toner (hereinafter, simply referred to as toner), and feeds the toner from a stirring member to a developing roller (developer carrier). The developing roller is provided with a magnet (regulating pole or the like) inside, and carries toner on the surface of the developing roller with the magnet (regulating pole or the like). By the rotation of the developing roller, the toner is conveyed to a part opposite a photosensitive member. The toner carried on the developing roller is then fed to the photosensitive member, and an electrostatic latent image on the photosensitive member is visualized as a toner image.
There are known developing devices which are provided with a regulating member comprising a magnetic body for regulating the thickness of toner so that the amount of toner conveyed to a part opposite the photosensitive member by the rotation of the developing roller is constant, and a magnet arranged on the upstream side of the regulating member in the developing roller rotation direction. In these developing devices, by arranging a magnet on the upstream side of the regulating member in the developing roller rotation direction, a magnetic pole with a polarity different from that of a regulating pole is induced at a tip end portion (end part on the developing roller side) of the regulating member, and toner that passes between the developing roller and the regulating member is regulated into a predetermined thickness.